Synchronization of satellite and terrestrial broadcast odfm signals

ABSTRACT

Synchronization of satellite and terrestrial broadcasts in a shared frequency arrangement is use in order to facilitate simultaneous reception of the broadcasts. A delay value is adjusted based on a synchronization between a first terrestrial broadcast and a satellite broadcast, and a delay value for a second terrestrial broadcast is adjusted based on a synchronization between the second terrestrial broadcast, the first terrestrial broadcast and the satellite broadcast. The adjustment of the relative delay values provides an improved reception pattern based on receipt of a shared frequency communication from multiple sources by improving a signal quality factor within at least selected regions of the coverage areas in which the relative delay values permit synchronization. This allows for synchronization lock between multiple substantially simultaneous broadcasts as determined by a cyclic prefix window of the broadcasts in overlapping coverage areas, useful for simultaneous satellite and terrestrial broadcasts using an OFDM format.

BACKGROUND

I. Field

The present invention relates generally to telecommunications and sharedfrequency broadcasting, such as used in terrestrial digitalmultimedia/television broadcasting systems.

II. Background

Typical broadcast distribution systems include terrestrial, satellite,cable, microwave and other transmission, for data broadcasting, Internetand other wideband multimedia information transmission, and forintegrated data service applications.

Terrestrial broadcasts have an advantage of strong signals within alocalized area. A disadvantage is that terrestrial broadcasts havesubstantial signal attenuation as a result of line-of-sight limitations.Satellite broadcasts, on the other hand, provide good area coverage, buthave limited power. In many cases, overhead obstructions, such asbuildings, trees, etc. limit satellite reception. In the case ofreception under varying conditions, such as by a mobile wirelesscommunication device (WCD), either satellite or terrestrial broadcastscan provide the best coverage, depending on the particular circumstancesat any given time.

A wireless communication device (WCD) includes but is not limited to auser equipment, station (STA), mobile station, fixed or mobilesubscriber unit, pager, or any other type of device capable of operatingin a wireless environment. When referred to hereafter, an access point(AP) includes but is not limited to a base station, Node-B, sitecontroller, WLAN access point or any other type of interfacing device ina wireless environment.

OFDM

OFDM (orthogonal frequency division multiplexing) is a multi-carriermodulation technique that effectively partitions the overall systembandwidth into multiple (N) orthogonal frequency subbands. Thesesubbands are also referred to as tones, sub-carriers, bins, andfrequency channels. With OFDM, each subband is associated with arespective sub-carrier that may be modulated with data.

In an OFDM system, a transmitter processes data to obtain modulationsymbols, and further performs OFDM modulation on the modulation symbolsto generate OFDM symbols, as described below. The transmitter thenconditions and transmits the OFDM symbols via a communication channel.The OFDM system may use a transmission structure whereby data istransmitted in symbols or groups of symbols, with each symboltransmission having a particular time duration. The symbol transmissiongenerally includes a cyclic prefix. The receiver typically needs toobtain accurate symbol timing in order to properly recover the data sentby the transmitter. For example, the receiver may need to know thetiming of each symbol transmission in order to properly recover the datasent in the symbol transmission. The receiver often does not know thetime at which each OFDM symbol is sent by the transmitter nor thepropagation delay introduced by the communication channel. The receiverwould then need to ascertain the timing of each OFDM symbol received viathe communication channel in order to properly perform the complementaryOFDM demodulation on the received OFDM symbol. There are varioustechniques used for accommodating variations in timing, including theuse of the cyclic prefix, training symbols and other techniques. Thisprovides a tolerance for synchronization errors; however the ability ofa receiver to accommodate lack of synchronization is limited.

Satellite Broadcasts

FIG. 1 is a diagram depicting the propagation delay effects of asatellite broadcast implemented from a geosynchronous orbit. Thesatellite itself is 35,786 km above mean sea level; however the distanceto any point on the earth is greater according to the distance of thatpoint from the orbital track of the satellite. The propagation delay isrepresented by arcs 111-119, so that, for example, a receiver near arc111 would be subject to less delay than a receiver near arc 118. Thechange in propagation delay is continuous with distance from thesatellite's sub-satellite point, so arcs 111-119 are not definedincremental boundaries. This change in propagation distance generally isgreatest in the north-south direction, with a declination correspondingto the orbital position of the satellite.

One aspect of shared frequency broadcasting using multiple sources isthat the relative delay in receipt of the signals varies according tothe position of the receiver with respect to the multiple sources. Ifthe multiple sources are equidistant from the receiver, then signalstransmitted at the same time will be synchronized. If the receiver iscloser to one transmitter, then the propagation delays will differ. Inthe case of satellite transmissions, there is a significant propagationdelay. In the case of geosynchronous satellites, the radio propagationdelay corresponds to 35,786 km above mean sea level plus the skewdistance to the receiver established by the geographical latitude of thereceiver.

If a signal is to be simultaneously received from both a terrestrialstation and a satellite, the transmission of the terrestrial stationmust be delayed with respect to that of the satellite. This delaychanges in accordance with the angle of inclination of the signal, whichroughly corresponds to the latitude of the receiver. This delay can beadjusted, and a receiver on the ground can continue to receive both aterrestrial signal and a satellite signal substantially simultaneously,provided that the signal times fall close to being within the timewindow defined by the cyclic prefix window. It is desirable that thesignal times fall within the time window defined by the cyclic prefixwindow or reasonably close to that time window because this reducesinterference. If the signal times fall within the time window defined bythe cyclic prefix window, the received signals exhibit a low amount ofinterference. It is possible to exceed the time window defined by thecyclic prefix by a small amount. Exceeding the time window can result ininterference; however, a small amount of interference is deemedacceptable because it does not substantially degrade the receivedsignals.

In the case of terrestrial broadcasts, adjacent stations can have theirsignals synchronized, or alternatively skewed, in a manner to optimizereception from the multiple terrestrial stations. This is particularlyadvantageous in regions within the coverage areas where signal strengthor signal quality are weakest. The areas covered by satellitebroadcasts, on the other hand, generally do not correspond to theterrestrial broadcast areas. As a result, the propagation delay of asatellite transmission when taken at different locations across a giventerrestrial broadcast area will vary. The delays in the satellitetransmission when taken at different locations across multipleterrestrial broadcast areas will vary to a significantly greater degree,particularly along a generally north-south direction. For this reason,setting synchronization between terrestrial stations in a conventionalfashion results in the terrestrial stations being out of sync with thesatellite or inoptimally synchronized with the satellite.

SUMMARY

Synchronization for single broadcasts transmitted from satellite andterrestrial broadcasts is performed by establishing a delay value for afirst terrestrial broadcast and adjusting the delay value based on asynchronization between the first terrestrial broadcast and a satellitebroadcast. In one configuration, a delay value is adjusted foradditional terrestrial broadcasts based on a synchronization between thesecond terrestrial broadcast, the first terrestrial broadcast and thesatellite broadcast.

In a particular configuration, a broadcast area of the first terrestrialbroadcast and an additional terrestrial broadcast is determined. Thedelay value is adjusted based on the synchronization between the firstterrestrial broadcast and the satellite broadcast for a coverage area ofthe first terrestrial broadcast and the additional terrestrialbroadcast. A delay value is adjusted based on the synchronization forsaid coverage area between the additional terrestrial broadcast and thesatellite broadcast. The relative delay values between the firstterrestrial broadcasts are adjusted based on synchronization between theterrestrial broadcasts and the satellite broadcast in order to obtain animproved reception pattern based on receipt of a shared frequencycommunication from multiple sources. The improvement is determined byimproving a signal quality factor within at least selected regions ofthe coverage areas in which the relative delay values permitsynchronization lock. The signal quality factor a quality measurementmay be one of a Signal to Interference plus Noise Ratio (SINR), a Signalto Interference Ratio (SIR), or a Signal to Noise Ratio (SNR). Theadjustment of the relative delay values may be performed by selectingcoverage areas according to actual or anticipated signal strength ofterrestrial broadcast signals and effecting said adjustments in therelative delay values in order to achieve the improved reception patternwithin the selected areas.

In one configuration, delay values are adjusted within a cyclic prefixwindow of the broadcasts in overlapping coverage areas. Adjusting of therelative delay values provides an optimization of the performance of thecombined terrestrial and satellite communication system.

In another configuration, a terrestrial station comprises a delaycircuit and a delay adjustment circuit. The delay adjustment circuit iscapable of establishing a delay value and adjusting the delay value bysynchronization for single broadcasts transmitted from satellite andterrestrial broadcasts, in which a delay value for a first terrestrialbroadcast is determined and adjusted based on a synchronization betweenthe first terrestrial broadcast and a satellite broadcast.

Various aspects and embodiments of the invention are described infurther detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and nature of the present invention will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings in which like reference charactersidentify correspondingly throughout and wherein:

FIG. 1 is a diagram depicting the propagation delay effects of asatellite broadcast implemented from a geosynchronous orbit.

FIG. 2 is a diagram showing a region in which a terrestrial broadcast isimplemented with a single terrestrial station in the depicted region.

FIG. 3 is a diagram showing region, in which a plurality of terrestrialstations are used to provide coverage in local terrestrial receptionareas.

FIG. 4 is a diagram showing the environment of FIG. 3, with thesuperposition of satellite broadcast areas represented according to apropagation time delay.

DETAILED DESCRIPTION

Overview

FIG. 2 is a diagram showing a region 200 in which a terrestrialbroadcast is implemented with a single terrestrial station 211 in thedepicted region 201. A plurality of WCDs 221, 222, 223, 224, 225, 226,227, 228, 229, 230, 231 are at various locations in the region 201. Forconvenience of explanation, the locations of the WCDs 221-231 arereferenced to the antennas. The ability to receive signals from thebroadcast station 211 is of course dependent on the distance of theindividual WCD from the station 211, as well as other characteristics ofthe signal propagation environment. If the area depicted by dashed line251 is presumed to be a strong coverage area and the area depicted bydashed line 252 is presumed to be a weaker coverage area, then WCDs222-224 would have good reception, and WCD 228 would be in a receptionarea with weaker reception. WCDs 221, 224, 226, 227 and 229 would beoutside the weaker coverage area 252 and would be less likely to receiveenough signal to have an acceptable quality of service (QoS). WCDs 230and 231 are probably unable to obtain sufficient signals from station211 to achieve service absent further augmentation.

The circles 251, 252 depicting the coverage area are presented forsimplicity; however the actual reception is varied as a result ofgeography and physical culture such as buildings, and can also be variedin shape according to antenna design. Significantly, circles 251, 252 donot represent defined boundaries, except that signal strength diminisheswith distance from the transmitter.

Also depicted is a representation of a satellite 271. The WCDs 221-231are also able to receive satellite signals because all of WCDs 221-231are in the satellite's coverage area if the satellite is not blocked. Asmentioned, the satellite signals are subject to their own limitationsrelated to signal propagation. Thus, if parts of areas 251 and 252 arelimited by overhead obstructions, better QoS is available from broadcaststation 211. Despite this, it is difficult to combine the satellitebroadcast with terrestrial broadcast unless the satellite broadcast withterrestrial broadcast are synchronized or nearly synchronized.

By setting delay between the terrestrial station 211 and the satellite271, it is possible to use shared frequency techniques such as providedby OFDM standards to combine the signals from the terrestrial station211 and the satellite 271. This would benefit reception for WCDs222-224, for example where urban obstructions make terrestrial broadcastreception difficult. This would also enhance reception for WCD 228 aswell as WCDs 222-224 by augmenting the signals received. In addition, tothe extent that WCDs 221, 224, 226, 227 and 229 are able to receivesignals from terrestrial station 211, the satellite and terrestrialsignals would augment each other. Additionally, WCDs 230 and 231, whileoutside of the coverage area of station 211, may be able to receivesufficient signals from station 211 to augment the satellite broadcast.

The signal synchronization between satellite 271 and terrestrial station211 comprises selecting a center point relative to synchronizationaccording to the distance to which the simultaneous reception isfunctional. Simultaneous reception is achieved by the signalssimultaneously received falling within a time window defined by thecyclic prefix window. For this reason, the adjustment is such that thesignals are received within the cyclic prefix window. This signalsynchronization is adjusted to achieve a desired timing relationship inareas where a combination of signals from the terrestrial station 211and the satellite 271 are most advantageous. In the case of the coveragearea represented in FIG. 2, the synchronization involves one groundstation 211 in the sense that an interaction between ground stations isnot considered significant.

FIG. 3 is a diagram showing region 200, in which a plurality ofterrestrial stations 311, 312, 313, 314 are used to provide coverage inlocal terrestrial reception areas represented schematically by circles321, 322, 323, 324. The reception areas 321-324 correspond to broadcaststations 311-314. The circles depicting the reception areas 321-324 arepresented for simplicity; however the actual reception is varied as aresult of geography and physical culture (buildings), and can also bevaried in shape according to antenna design. Significantly, the circles321-322 do not represent defined boundaries, except that signal strengthdiminishes with distance from the transmitter. In a shared frequencymultiple broadcast OFDM environment, the boundaries (circles 321-322)are even less defined because reception can be significantly enhanced bycombining reception from multiple sources.

Still referring to FIG. 3, WCDs 221-231 are depicted at the variouslocations, with the locations of the WCDs 221-231 referenced by thepositions of the antennas. In the diagram, WCDs 221, 222, 225, 227, 228are within a single one of the reception areas depicted by circles321-322. WCD 223 is within multiple ones of reception areas, depicted bycircles 321, 322. WCD 224 is within multiple ones of reception areas,depicted by circles 321, 323. WCD 226 is within multiple reception areasdepicted by circles 322, 324. WCDs 229, 230 and 231 are outside of theboundaries indicated by circles 321-322.

The relative signal strength of each of the reception areas had not beenspecifically defined. If the signal strengths within circles 321-324 aresufficient for reception from a single station, then any WCD 221-228within any of circles 321-324 would theoretically have sufficient signalstrength for proper reception. The terminology “theoretically” is usedbecause as mentioned above, there are variations caused by the physicalenvironment. In a shared frequency multiple broadcast OFDM environment,reception would also be available outside of the circles 321-324 if theWCD is sufficiently close to multiple stations. In FIG. 3, this wouldapply to WCD 229, which is near stations 311, 313 and 314, but is notwithin any of circles 321, 323, 324. WCDs 230 and 231 would be lesslikely to benefit from proximity to multiple stations. In the case ofWCD 230, this is a result of WCD 230 being outside of its nearestreception area 324 and much further from the next nearest receptionareas 321-323. Similarly, in the case of WCD 231, this is a result ofWCD 231 being outside of its nearest reception area 323 and much furtherfrom reception areas 321, 322, 324. In order for WCDs 230, 231 to obtainreception, the signals from stations 321-324 must be sufficient to allowthe WCD to process the combined signals according to the sharedfrequency multiple broadcast OFDM configuration.

It is alternatively possible to define circles 321-324 as having lessthan a minimum signal strength for reception from a single station. Inthat case, WCD 224 would have good reception because it is near station313, but WCD 228 would have poor reception because it is on the outerfringe. WCD 223 would be on the outer fringes of areas 321 and 322 butwould benefit from multiple broadcasts from a combination of stations321, 322. The terrestrial reception from multiple stations 321, 322would be sufficient to provide good reception. In either case, thereception by any of the WCDs 221-231 is dependent on the distance fromthe stations 311-324 and the ability of the WCDs 221-231 to combinesignals from multiple stations 311-324 in a shared frequency multiplebroadcast OFDM environment.

In general, without the satellite synchronization issue, it would bedesirable to have the base stations to be synchronized in mostinstances. An exception to this is, for example, the case in which acell has better propagation conditions. In that case, its signal maypenetrate other cells further. Such a cell may have an earlier starttime than its neighbor cells. The adjustment of satellitesynchronization would overlay such an adjustment of the synchronizationof cells based on propagation conditions.

FIG. 4 is a diagram showing the environment of FIG. 3, but with thesuperposition of satellite broadcast delay contours 471, 472, 473, 474,475, 476, 477. The satellite (e.g., satellite 271 as represented in FIG.2) can be used to augment terrestrial signals from terrestrial stations311-314. Reception by WCDs 211-231 depends on the availability of eithera signal from the satellite, from terrestrial stations 311-314 or anycombination of the satellite and terrestrial stations. In order for thecombination to work, the signals must be substantially simultaneouslyreceived. As in the case of a single terrestrial broadcast station (211,FIG. 2), simultaneous reception of satellite signals and terrestrialsignals is such that the signals are received within a time windowdefined by the cyclic prefix window.

The satellite transmission is represented by the delay contours 471-477in order to graphically depict a time lag resulting from signalpropagation of the satellite signal, however the change in signalpropagation is continuous. The delay contours 471-477 are modelsrepresenting the relative time delays for satellite transmissionresulting from propagation delay.

Still referring to FIG. 4, if the satellite transmission is integratedwith transmissions from the terrestrial stations 311-314, then WCDs229-231 would be in at least the satellite reception area generallyrepresented by delay contours 475, 476. Looking at WCD 230, it is likelythat it can also receive signals from terrestrial station 314, in whichcase, WCD 230's reception is a combination of signals from the satellite(indicated at delay contour 475) and terrestrial station 314. Similarly,WCD 229, is likely to receive signals from terrestrial stations 311, 313and 314, in combination with signals from the satellite approximatelyhalf-way between delay contours 475 and 476.

WCD 228 is depicted within a coverage area 323 of terrestrial station313, but near the fringe of coverage area 323. If WCD 323 is able toreceive signals from the satellite, the reception by WCD 228 would be acombination of signals from terrestrial station 313 and signals from thesatellite (indicated at delay contour 475). WCD 223 is likely able toreceive a combination of signals from two terrestrial stations 311, 312and signals from the satellite (indicated at delay contours 472 and473).

WCD 225 is able to receive a combination of signals from the satelliteand terrestrial station 313; however the close proximity of WCD 225 tostation 313 means that in most instances, the reception from station 313alone will provide approximately the same quality of service (QoS) as acombination of signals from terrestrial station 313 and signals from thesatellite at delay contour 474. When configuring the signals, thereception of WCD 225 would not be a significant factor because it islikely that WCD 225 will generally have good QoS. Regardless, to theextent that the signals from the satellite and terrestrial station 313fall within the cyclic prefix window, WCD 225 is more able to overcomesignal fading and other effects on the signal from terrestrial station313.

When configuring the terrestrial stations 311-315 without considerationof satellite broadcasts, it is possible to set the timing differencebetween transmissions so that signals from the different stations311-315 are best received in the fringe areas. If a WCD is equidistantto two stations, then the received signals would be timed so that thereis no time shift between the two stations. This is not true in the caseof satellite broadcasts combined with terrestrial stations because thepropagation delay follows a different pattern. Referring to FIG. 4,signals within the different areas represented by delay contours 471-477experience different signal delays even though they have a common originat the satellite. As mentioned, this delay change is continuous; thedelay contours 471-477 being provided for simplicity of depiction. Thedelay value is determined by adjusting the delay for achieving theoptimum coverage based on a signal quality factor. The signal qualityvalue factor is determined by a signal quality measurement such assignal to interference plus noise ratio (SINR). Different approaches maybe used in determining the signal quality, so the a quality measurementmay be selected from one at least one of a SINR, a signal tointerference ratio (SIR), or a signal to noise ratio (SNR).

If the combined system is to be matched to provide a favorable timingrelationship between the different transmission sources, thenaccommodation is made for the propagation delay differences withterrestrial stations 311-315 according to delay contours 471-477. Thiscan conflict with the best timing relationship between terrestrialstations 311-315, so the ideal timing relationship is not necessarilythat of a match between the propagation delays at delay contours 471-477and is not that of full synchronization of terrestrial stations 311-315.

In the case of one or more cells having better propagation conditions,the synchronization is adjusted accordingly. This is because it islikely that the signals from cells with better propagation conditionsmay penetrate other cells further. Such cells may have an earlier starttime than its neighbor cells. In that case, the satellitesynchronization based on delay contours remains overlaid on thatadjustment of synchronization.

When multiple terrestrial base stations are synchronizing with thesatellite signal, all other things being equal, the base stations thatare further north (more exactly along a northerly direction from thesub-satellite point) will delay their transmissions more than thestations further south so as to try to compensate for the increaseddelay of the satellite signal reaching the more northerly cells. Theexact value by which the delay is increased is determined by determiningwhat delay will improve one of the signal quality factors mentionedabove.

CONCLUSION

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a general purpose processor, a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,microprocessor, or state machine. A processor may also be implemented asa combination of computing devices, e.g., a combination of a DSP and amicroprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

The methods or algorithms described in connection with the embodimentsdisclosed herein may be embodied directly in hardware, in a softwaremodule executed by a microprocessor, or in a combination of the two. Asoftware module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. A storagemedium may be coupled to the processor such that the processor can readinformation from, and write information to, the storage medium. In thealternative, the storage medium may be integral to the processor. Theprocessor and the storage medium may reside in an ASIC. The ASIC mayreside in a user terminal. In the alternative, the processor and thestorage medium may reside as discrete components in a user terminal.

The previous description of the disclosed embodiments is provided toenable a person skilled in the art to make or use the present invention.Various modifications to these embodiments will be readily apparent tothose skilled in the art, and the generic principles defined herein maybe applied as will be apparent to those skilled in the art. For example,one or more elements can be rearranged and/or combined, or additionalelements may be added. Thus, the present invention is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope consistent with the principles and novel features disclosedherein.

The techniques and modules described herein may be implemented byvarious means. For example, these techniques may be implemented inhardware, software, or a combination thereof. For a hardwareimplementation, the processing units within an access point or an accessterminal may be implemented within one or more application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, other electronic units designed toperform the functions described herein, or a combination thereof.

For a software implementation, the techniques described herein may beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. The software codes may be storedin memory units and executed by processors or demodulators. The memoryunit may be implemented within the processor or external to theprocessor, in which case it can be communicatively coupled to theprocessor via various means.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the features,functions, operations, and embodiments disclosed herein. Variousmodifications to these embodiments may be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other embodiments without departing from their spirit orscope. Thus, the present disclosure is not intended to be limited to theembodiments shown herein but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein.

1. A method for determining a synchronization for single broadcasts frommultiple sources, the method comprising: establishing a delay value forat least a first terrestrial broadcast; and adjusting the delay valuebased on a synchronization between the first terrestrial broadcast and asatellite broadcast.
 2. The method of claim 1, further comprisingadjusting a delay value for at least a second terrestrial broadcastbased on a synchronization between the second terrestrial broadcast, thefirst terrestrial broadcast and the satellite broadcast.
 3. The methodof claim 1, further comprising: determining a broadcast area of thefirst terrestrial broadcast and at least a second terrestrial broadcast;adjusting the delay value based on the synchronization between the firstterrestrial broadcast and the satellite broadcast for a coverage area ofthe first terrestrial broadcast and the second terrestrial broadcast;adjusting a delay value based on the synchronization for said coveragearea between the second terrestrial broadcast and the satellitebroadcast; and adjusting the relative delay values between the firstterrestrial broadcast and the second terrestrial broadcast based on thesynchronization between the first terrestrial broadcast, the secondterrestrial broadcast and the satellite broadcast in order to obtain animproved reception pattern based on receipt of a shared frequencycommunication from multiple sources by improving a signal quality factorwithin at least selected regions of the coverage areas in which therelative delay values permit synchronization lock.
 4. The method ofclaim 3, comprising selecting as the signal quality factor a qualitymeasurement selected from one at least one of a Signal to Interferenceplus Noise Ratio (SINR), a Signal to Interference Ratio (SIR), or aSignal to Noise Ratio (SNR).
 5. The method of claim 1, comprising: usingas a basis for the adjustment of the delay value, a signal qualityfactor within at least selected regions of the coverage areas in whichthe relative delay values permit synchronization lock; selecting as thesignal quality factor a quality measurement selected from one of atleast one of a Signal to Interference plus Noise Ratio (SINR), a Signalto Interference Ratio (SIR), or a Signal to Noise Ratio (SNR); and theadjusting the relative delay values performed by selecting coverageareas according to actual or anticipated signal strength of terrestrialbroadcast signals and effecting said adjustments in the relative delayvalues in order to achieve the improved reception pattern within theselected areas.
 6. The method of claim 1, comprising: using as a basisfor the adjustment of the delay value, a signal quality factor within atleast selected regions of the coverage areas in which the relative delayvalues permit synchronization lock; selecting as the signal qualityfactor a quality measurement selected from one of at least one of aSignal to Interference plus Noise Ratio (SINR), a Signal to InterferenceRatio (SIR), or a Signal to Noise Ratio (SNR); and the adjusting therelative delay values performed by maximizing the quality measurementover an area of the terrestrial broadcast signals corresponding to ananticipated coverage area of the terrestrial broadcast and effectingsaid adjustments in the relative delay values in order to achieve theimproved reception pattern within the anticipated coverage area of theterrestrial broadcast.
 7. The method of claim 1, comprising: using as abasis for the adjustment of the delay value, a signal quality factorwithin at least selected regions of the coverage areas in which therelative delay values permit synchronization lock; selecting as thesignal quality factor a quality measurement selected from one of atleast one of a Signal to Interference plus Noise Ratio (SINR), a Signalto Interference Ratio (SIR), or a Signal to Noise Ratio (SNR); theadjusting the delay values performed by maximizing the qualitymeasurement over an area of the terrestrial broadcast signalscorresponding to an anticipated coverage area of the terrestrialbroadcast; and weighting the resultant quality measurements inaccordance with a signal power or signal quality measurement, therebyusing the adjustment of the relative delay values in a manner to benefitportions of the area of terrestrial broadcast signals having the leastsignal power or signal quality.
 8. The method of claim 1, furthercomprising: determining a time window for synchronization lock betweenmultiple substantially simultaneous broadcasts; and determining amaximum cell coverage area of a terrestrial broadcast for permittingsynchronization between the satellite broadcast and the terrestrialbroadcast while remaining within the determined time window forsynchronization lock; performing the adjustment of the delay valuesbased on the synchronization between the terrestrial broadcast and thesatellite broadcast within the maximum cell coverage area.
 9. The methodof claim 1, further comprising: determining a time window forsynchronization lock between multiple substantially simultaneousbroadcasts as determined by a cyclic prefix window of the broadcasts inoverlapping coverage areas; and determining a maximum cell coverage areaof a terrestrial broadcast for permitting synchronization between thesatellite broadcast and the terrestrial broadcast while remaining withinthe determined time window for synchronization lock; performing theadjustment of the delay values based on the synchronization between theterrestrial broadcast and the satellite broadcast within the maximumcell coverage area.
 10. The method of claim 1, further comprisingperforming an optimization calculation of a delay value for a secondterrestrial broadcast based on a synchronization between the secondterrestrial broadcast, the first terrestrial broadcast and the satellitebroadcast.
 11. The method of claim 1, further whereby, in thesynchronization of terrestrial base stations, a base stations further ina northerly direction from a sub-satellite point delays transmissionsmore than base stations closer to the sub-satellite point, therebycompensating for an increased delay of satellite signals reaching aterrestrial cell established by the base station.
 12. The method ofclaim 1, further comprising the delay established by an improvement ofat least one signal quality measurement whereby, in the synchronizationof terrestrial base stations, a base stations further in a northerlydirection from a sub-satellite point delays transmissions more than basestations closer to the sub-satellite point, thereby compensating for anincreased delay of satellite signals reaching a terrestrial cellestablished by the base station.
 13. A terrestrial station comprising: adelay circuit; a delay adjustment circuit, capable of establishing adelay value and adjusting the delay value in accordance with claim 1.14. A method for enhancing performance of a combined terrestrial andsatellite communication system to provide improved reception incommunications implemented by shared frequency communicationsubstantially simultaneously with multiple communication devices, themethod comprising: establishing a delay value for at least a firstterrestrial broadcast; adjusting the delay value based on asynchronization between the terrestrial broadcast and a satellitebroadcast; and adjusting the relative delay values between the firstterrestrial broadcast and a second terrestrial broadcast based on thesynchronization between the first terrestrial broadcast, the secondterrestrial broadcast and the satellite broadcast in order to obtain animproved reception pattern based on substantially simultaneous receiptof a shared frequency communication from multiple sources.
 15. Themethod of claim 14, further comprising adjusting a delay value for asecond terrestrial broadcast based on a synchronization between thesecond terrestrial broadcast, the first terrestrial broadcast and thesatellite broadcast.
 16. The method of claim 14, further comprising:determining a broadcast area of the first terrestrial broadcast and thesecond terrestrial broadcast; adjusting the delay value based on thesynchronization between the first terrestrial broadcast and thesatellite broadcast for a coverage area of the first terrestrialbroadcast and the second terrestrial broadcast; and adjusting a delayvalue based on the synchronization for said coverage area between thesecond terrestrial broadcast and the satellite broadcast, the adjustmentof the delay values providing the improved reception in communications.17. The method of claim 16, further comprising maintaining the delayvalues within a cyclic prefix window of the broadcasts in overlappingcoverage areas.
 18. The method of claim 14, wherein the adjusting of therelative delay values provides an optimization of the performance of thecombined terrestrial and satellite communication system.
 19. Aterrestrial station comprising: a delay circuit; a delay adjustmentcircuit, capable of establishing a delay value and adjusting the delayvalue in accordance with claim
 14. 20. A terrestrial station capable ofproviding transmissions for simultaneous reception from said terrestrialstation and a satellite transmission, the terrestrial stationcomprising: means for establishing a delay value for the terrestrialstation; and means for adjusting the delay value based on asynchronization between the terrestrial broadcast and a satellitebroadcast in accordance with anticipated propagation of the signals fromthe terrestrial broadcast and the satellite broadcast, so as to maintainsignals at a predetermined reception area substantially within a rangeof synchronization as determined by a cyclic prefix window of thebroadcasts in overlapping coverage areas.
 21. The terrestrial station ofclaim 20, further comprising adjusting a delay value for at least asecond terrestrial broadcast based on a synchronization between thesecond terrestrial broadcast, the first terrestrial broadcast and thesatellite broadcast.
 22. The terrestrial station of claim 20, furthercomprising: means for providing a determination of a broadcast area ofthe first terrestrial broadcast and at least a second terrestrialbroadcast; means for adjusting the delay value based on thesynchronization between the first terrestrial broadcast and thesatellite broadcast for a coverage area of the first terrestrialbroadcast and the second terrestrial broadcast; means for adjusting adelay value based on the synchronization for said coverage area betweenthe second terrestrial broadcast and the satellite broadcast; and meansfor adjusting the relative delay values between the first terrestrialbroadcast and the second terrestrial broadcast based on thesynchronization between the first terrestrial broadcast, the secondterrestrial broadcast and the satellite broadcast in order to obtain animproved reception pattern based on receipt of a shared frequencycommunication from multiple sources by improving a signal quality factorwithin at least selected regions of the coverage areas in which therelative delay values permit synchronization lock.
 23. The terrestrialstation of claim 20, further comprising the means for establishing adelay value establishes the delay value by an improvement of at leastone signal quality measurement whereby, in the synchronization ofterrestrial base stations, a base station further in a northerlydirection from a sub-satellite point delay transmissions more than ifcloser to the sub-satellite point, thereby compensating for an increaseddelay of satellite signals reaching a terrestrial cell established bythe base station.
 24. A terrestrial station capable of providingenhanced performance of a combined terrestrial and satellitecommunication to provide improved reception in communicationsimplemented by shared frequency communication substantiallysimultaneously with multiple communication devices, the terrestrialstation comprising: means for establishing a delay value for at least afirst terrestrial broadcast; means for adjusting the delay value basedon a synchronization between the terrestrial broadcast and a satellitebroadcast; and means for adjusting the relative delay values between thefirst terrestrial broadcast and a second terrestrial broadcast based onthe synchronization between the first terrestrial broadcast, the secondterrestrial broadcast and the satellite broadcast in order to obtain animproved reception pattern based on substantially simultaneous receiptof a shared frequency communication from multiple sources.
 25. A storagemedium for use in enhancing performance of a combined terrestrial andsatellite communication system to provide improved reception incommunications implemented by shared frequency communicationsubstantially simultaneously with multiple communication devices, thestorage medium comprising instructions when executed by a processingmodule for: determining a delay value for a satellite broadcastcorresponding to at least a first terrestrial broadcast location;establishing a delay value for at least a first terrestrial broadcastapplicable to the first terrestrial broadcast location; and adjustingthe delay value for the first terrestrial broadcast based on asynchronization between the first terrestrial broadcast and a satellitebroadcast.
 26. The storage medium of claim 25, further comprisinginstructions for adjusting a delay value for at least a secondterrestrial broadcast based on a synchronization between the secondterrestrial broadcast, the first terrestrial broadcast and the satellitebroadcast, the adjustment performed to obtain an improved receptionpattern based on substantially simultaneous receipt of a sharedfrequency communication from multiple sources corresponding to thesatellite broadcast and the first and second terrestrial broadcasts.